Injector nozzle



Dec. 1, 1942. J. C. w. FRAZERETAL 2,303,992

INJECTOR NOZZLE Filed Oct. 9, 1940 91 Z FENTOR. WITNE6.S 6. @Wlh mm BYma a 1AM 7 M W1 M 1%.; ATTORNEYS.

Patented Dec. 1, 1942 Y INJECTOR NOZZLE Joseph C. W. Frazer, Baltimore,Md., and Owen G.

. Bennett, Pittsburgh, Pa.

Application October 9, 1940, Serial No. 360,384

3 Claims.

This invention relates to injectors for entraining a gas by a fluidflowing through the injector, and more particularly to injector nozzlesfor use with fluids of varying volume or pressure.

It is known that when a fluid issues at a certain velocity from aninjector nozzle having a passage or orifice of flxed dimensions, thefluid entrains at a constant rate the gas surrounding the nozzle at theinlet of the injection throat or Venturi tube. It is also known that ifthe velocity of the fluid changes, due to change in volume or pressure,the rate of gas entrainment is varied thereby, but not in propoijtion tothe volume or fluid flowing from the injector nozzle to the injectionthroat. Consequently, an injector that is designed to functionsatisfactorily with a fluid issuing from its nozzle at a certainvelocity may operate unsatisfactorily in case the velocity of the fluidvaries, as it may do in some instances, as in the case of internalcombustion engines.

Various processes have been proposed for eliminating carbon monoxide andother combustible constituents of internal combustion engine exhaustgases which involve mixing the gases with air to supply oxygen for thecombustion of such constituents. For various reasons the amount of airmixed with the gases should not greatly exceed that needed to supplysuflicient oxygen for the combustion, but difficulties have .beenencountered in applying injectors for that purpose. Thus, the volume ofexhaust gases varies as the engine idles, labors and changes speed, andthe content of combustible matter likewise is varied through the sameand other factors. Hence the amounts of air needed vary widely, andexperience has shown that injectors of ordinary constructions areincapable of properly supplying air to the exhaust gases over the entirerange of operating conditions. For example, injector nozzles designed tosupply air properly under certain conditions of operation fail to supplysufficient air if the volume of exhaust gases, or their pressure,decreases, while their increase may, and commonly des,.c,ause theinjector to choke. Also, devices of modified construction, such as thoseembodying a plurality of nozzles, have been found to be unsatisfactory,either practically or economically. For this and other purposes it wouldbe desirable to have an injector capable of supplying definite amountsof gas under widely varying operating conditions.

It is among the objects of this invention to provide an injector whichfunctions satisfactorily over widely varying volumes and pressures offluid flowing therethrough, which includes an injector nozzle from whichfluid issues at a constant velocity regardless of changes in its volumeand pressure, and which is dependable in operation, simple inconstruction, and relatively inexpensive.

In accordance with this invention there is provided an injector nozzlehaving a fluid passage a portion of the wall of which is normallyinclined toward the opposite portion of the passage wall to close ornearly close the passage when fluid flows through it. This convergingportion of the wall is adapted to be moved outwardly by the pressure offluid flowing through the nozzle whereby the area of the outlet iscontrolled by the pressure of fluid flowing through the nozzle so thatthe velocity of the fluid issuing from the outlet remains substantiallyconstant at all times. More specifically, the wall of the nozzle passagehas at least one portion the inner end of which is mounted in flxedposition and the outer end of which is movable toward and away from theopposite portion of the passage wall to vary the area of the outlet ofthe passage. This movable portion of the wall is biased inwardly in anysuitable manner, but is adapted to be moved outwardly by the pressure ofthe fluid in the passage.

The invention is illustrated in the accompanying drawing in which Fig. 1is a side view of the injector nozzle showing it disposed at the inletend of an injection throat; Fig. 2 is a longitudinal section through thenozzle, taken on the line 11-11 of Fig. 1; Fig. 3 is an end view of thenozzle; and Fig. 4 is a view, similar to Fig. 2, of a modifiedembodiment.

Referring. to Figs. 1, 2 and 3 of the drawing, an annular base memer Ihas a threaded nipple 2 at one end adapted to be connected by anysuitable condult to the supply of fluid that is to flow through thenozzle and into a Venturi tube 3 forming the injection throat. The basemember is provided with a central opening 4 and with a pair of opposed,fixed wall members 5 projecting from the base member axially of theopening from diametrically opposite sides thereof. Disposed between thefixed wall members is a second pair of wall members 6 forming therewitha conduit or passage through the nozzle for fluid flowing through basemember opening 4. The inner faces of wall members -5 are parallel, andwall members 6 are formed of a pair of thin metal strips disposedbetween walls 5 at right angles theretowith their opposite edges insliding contact with the parallel surfaces. The inner ends of thesestrips are secured to the base member on diametrically opposite sides ofthe opening therethrough. This is preferably accomplished by connectingthe inner ends of the strips by screws I to the outer surfaces of shortwall portions .8 of base member I between fixed members 5.

It is a feature of this invention that the size of the outlet from thepassage through the nozzle is controlled by the fluid flowingtherethrough so that the velocity of the fluid issuing from the nozzlewill remain substantially constant regardless of variations in volumeand pressure of the fluid flowing through the opening in base I.Accordingly, the metal strips are resilient and are so mounted betweenfixed members thattheir outer edges approach each other and arepreferably in contact when the injector is not in use. This ispreferably brought about by beveling the outer faces 01' short wallportions 8 so that strips 6 attached thereto converge toward the outerend of the nozzle. The flow of fluid through the nozzle flexes theresilient strips and spreads their outer ends apart so that there isprovided 9. variably apertured outlet whose area is controlled by thepressure of fluid flowing through the nozzle. If the pressure of thefluid increases, the strips are separated still further. On the otherhand, when the pressure decreases, the resiliency of the strips bringstheir free ends back toward each other and diminishes the size of thepassage outlet accordingly. r

The embodiment of the invention shown in section in Fig. 4 isfundamentally the same in construction and operation as the one justdescribed. However, instead' of being provided with only two resilientstrips, it has a plurality of overlapping resilient strips ll, l2, l3,l4, l5 and I6 at each of two sides of the passage through the nozzle,and each set of these strips is covered and protected by a rigid plateH. The inner end of each plate and the inner ends of the underly ingresilient strips are all secured to a wall portion 8 of the base memberi by screws 1. The rigid plates are bent outwardly permanently so thatthey will not interfere with the movements of the resilient strips. Theinnermost strip of each set is relatively short, and each succeedingadjoining strip is longer than the preceding one. Due to thisarrangement of the resilient strips vibration of the long outer stripsis dampened and the noise resulting therefrom thereby eliminated.Nevertheless, no restraint is placed on the movements of the strips forchanging the size of the nozzle passage in accordance with the pressureof the fluid flowing through the nozzle.

Although the injectors disclosed herein are intended for use whereverthe volume and pressure of fluid flowing through the nozzle fluctuatesmaterially, they are especially suitable for use in the treatment ofexhaust gases from internal combustion engines to eliminate poisonousand noxious gases and vapors, and combustible constituents in general,from the exhaust gases. The gases are first mixed with sufficient oxygento oxidize their combustible constituents and the mixture is thensubjected to a catalyst capable of efiecting such oxidation. The oxygenis added to the combustible constituents by mixing air with them,generally by means of an injector. However, the volume of exhaust gasesfrom an automobile engine fluctuates widely, due to engine speed,carburetor setting and other conditions, and heretofore it has beenfound to be virtually impossible to properly treat those gases under allconditions encountered.

This important problem is solved in a dependable, inexpensive andautomatic manner by the invention disclosed herein. When the volume ofexhaust gases is quite small, the nozzle orifice is likewise small sothat the velocity of the gases issuing therefrom is sufficient toentrain enough air to oxidize their combustible constituents. If thevolume of gases increases, the nozzle orifice is opened wider, wherebythe velocity of the gases does not increase to an extent where theamount 76 of air entrained bears an improper relation to the increasedvolume of gases. Consequently, the exhaust gases are properly treatedregardless of fluctuations in their volume.

With

operation at all times. The only part of the nozzle that presents anyproblem in this connection is the metal strips. Although they may bemade in different thicknesses and of different compositiced otherwisethan as specifically illustrated and described.

We claim:

1. An injector nozzle comprising a base member provided with an openingtherethrough, a pair of opposed fixed wall members associated with saidbase member at opposite sides of said opening, and a pair of flexiblewall members disposed between said fixed members with their inner endsconnected to said base and converging toward each other outwardly fromsaid base, said flexible walls forming with said fixed walls a conduitfor fluid flowing through said opening, said flexible walls beingresponsive to the pressure of said fluid to vary the area of the outletof said conduit, and each of said flexible walls including a pluralityof resilient strip members the inner one of which is shorter than theouter one.

2. An injector nozzle comprising a base member provided with an openingtherethrough, a pair of opposed fixed wall members associated with saidbase member at opposite sides of said opening, a pair of flexible wallmembers disposed between said fixed members with their inner endsconnected to said base and converging toward each other outwardly fromsaid base, said flexible walls forming with said fixed walls a conduitfor fluid flowing through said opening, said flexible walls beingresponsive to the pressure of said fluid to vary the area of the outletof said conduit, and a substantially rigid plate overlying eachof saidflexible walls with its major portion spaced therefrom, and each of saidflexible walls including a plurality of resilient strip members theinner one of which is shorter than the outer one.

3. An injector nozzle provided with a passage for fluid conductedthereto, said passage having a wall at least a portion of which isflexible and normally inclined toward the opposite portion of thepassage wall, and said flexible portion of the wall including aplurality of resilient strip members superimposed for a portion of theirlength with the inner one shorter than the outer one, and said stripmembers being adapted to be moved outwardly by the, pressure of fluidflowing through said passage whereby the size of the passage outlet iscontrolled and thereby the outlet velocity of the fluid is maintainedsubstantially constant.

JOSEPH C. W. FRAZER. OWEN G. BENNETT.

